Tires for a Kazuma 150 Falcon

I purchased my grandson a Kazuma 150. Most of the places we ride are either hard ground with sand on top, or just very sandy. The stock tires perform poorly in the sand. If the ground is firm underneath it does OK. I don't want to put paddles on it if I can help it. But I was wondering what tires everyone is running on these? If I remeber correctly it has 19-9.50-8 tires on it. It has plenty of power and I was thinking about larger diameter tires. Oh, and I will get some spacers for the wheels to help with the stability. I did a search on the forum and found dead links and pictures that did not work so I guess I am gonna ask the question again.
Thanks,
Ray

Carlisle Badlands 18x11-8 in the rear.
Maxxis Front Pro 20x7-8 on the front.

This combination works great in everything but sticky Ohio mud.